2015-07-10T06:50:56ZExperimental reintroduction of northern wormwood (Artemisia campestris var. wormskioldii), a rare species of dynamic cobble bar environments on the Columbia Riverhttp://hdl.handle.net/1957/40121
Experimental reintroduction of northern wormwood (Artemisia campestris var. wormskioldii), a rare species of dynamic cobble bar environments on the Columbia River
Brickner, Alexis H.
Rare plant reintroductions that result in additional or more viable wild populations are important conservation tools for maintaining biodiverse ecosystems. Ideally, such projects are best designed as experiments, to improve biological and ecological knowledge of the selected species and monitoring long-term results. Northern wormwood (Artemisia campestris var. wormskioldii: Asteraceae), a nearly extinct, early seral species restricted to Columbia River riparian habitat, is only known from two native populations in Washington, set 300 river kilometers apart. Both populations are declining and show minimal recruitment. In cooperation with the U.S. Fish and Wildlife Service and Army Corps of Engineers, we set up an experimental reintroduction project with the objectives of: (1) investigating the effect of environmental factors on survival of northern wormwood, to gain a better understanding of this species' habitat requirements; and (2) creating a second viable population to further recovery objectives. To achieve these goals, we obtained seeds from multiple sources in order to increase the diversity of the founding population and determine germination rates for each source. We then planted 2,100 greenhouse-grown plants on Rufus Island, Oregon, in October, 2011. We transplanted 1,450 of these in experimental plots to examine the impacts of three environmental factors: (1) substrate type; (2) distance from the water line; and (3) presence or absence of the invasive shrub false indigo (Amorpha fruticosa). The remaining plants were placed in four surplus populations in order to increase the founding population size and create a viable population. Results showed that seeds germinated at different rates across sources and years. Success of transplants was measured by survivorship and reproductive output. Transplants were most successful when planted in sand substrate and at least nine meters from the water line. The presence of false indigo, a listed invasive species, did not have a significant effect on survival of transplants. Reproductive output showed that this population produced viable seeds and recruitment was observed by way of eleven seedlings. The results from this project present new information on northern wormwood habitat requirements, as well as provide a protocol for future recovery efforts.
Graduation date: 2014
2013-06-10T00:00:00ZDrivers of arbuscular mycorrhizal fungal community composition in roots : hosts, neighbors, and environmenthttp://hdl.handle.net/1957/34446
Drivers of arbuscular mycorrhizal fungal community composition in roots : hosts, neighbors, and environment
Phillips, Wendy S.
The vast majority of terrestrial plant species live in symbiosis with arbuscular mycorrhizal fungi (AMF). AMF and plants live in complex networks, with roots of individual plants hosting multiple AMF, and single AMF colonizing multiple plants concurrently. Through the exchange of resources, the two partners of this symbiosis can have great effects on each other, effects which can ripple through both communities. What determines the patterns of associations between the partners is still largely unknown. In this dissertation, I examine a variety of factors, and in particular host identity, that could drive the community composition of AMF in roots.
I began by surveying the diversity of AMF in roots of 12 plant species at a remnant bunchgrass prairie in Oregon, U.S.A. (Chapter 2). To do that, I first designed new primers for use in polymerase chain reaction (PCR) to specifically amplify DNA from all Glomeromycota species. Using those primers, I found 36 distinct AMF phylogenetic groups, or operational taxonomic units (OTUs) in the roots from the
prairie. The proportion of OTUs in the basal order Archaeosporales was greater than in many other environmental surveys. I also conducted an in silico analysis to predict how effectively previously published primers would detect the whole diversity of OTUs I detected.
I then assayed AMF community composition in the roots of 50 plants from nine plant species (Chapter 3). To do that, I designed primers specific to 18 of the OTUs detected in the initial field survey and used them to test for the presence of each OTU in the roots individual plants. I used that data to test if AMF community composition in individual roots correlated with host identity, spatial distribution, or soil characteristics. I found host identity was associated with both the richness and the structure of root AMF communities, while spatial distribution and soil characteristics were not.
Finally, I performed an experimental test of the effect of host identity and community context on AMF community assembly (Chapter 4). I grew plants from four native perennial plant species, including two common and two federally endangered plants, either individually or in a community of four plants (with one plant of each species). I analyzed the AMF community composition in the roots of all plants after 12 weeks of growth with exposure to a uniform mix of field soil as inoculum. I found that host species identity affected root AMF richness and community composition, and community context affected AMF richness. Only one of the endangered species was highly colonized by AMF, and I did not detect unique AMF communities associated with it.
This dissertation provides information on the diversity of AMF at a remnant bunchgrass prairie, an ecosystem which has been the subject of very few studies of AMF. Although a complex mix of factors interact to determine AMF community composition in roots, this work provides strong evidence that host identity plays a major role in that process.
Graduation date: 2013
2012-09-06T00:00:00ZDefining agricultural sustainability in the Marys River region of Oregonhttp://hdl.handle.net/1957/33786
Defining agricultural sustainability in the Marys River region of Oregon
Stanton, Michael (Michael Sean)
This ethnographic study explores the social aspects of agricultural land-use in the Marys River region. The study seeks to understand how farmers define sustainability and how their views on agricultural issues help to define a sense of place and identity in the Marys River region, within the context of the globalized agricultural system. This project builds on past research utilizing the theory and praxis of political ecology, but also incorporates elements of bioregionalism to develop a theoretical model of regional political ecology for an integrated and multidisciplinary approach to answering the research questions. The study asks:
1) How do farmers in the Marys River region define agricultural sustainability?
2) What methods do farmers use to develop more sustainable agroecosystems?
3) What do farmers consider to be the most important issues in developing a more sustainable regional community within the globalized system of agriculture?
A critical synthesis of information is developed establishing bioregional political ecology within the conceptual framework of the project. The study then describes the broad social and economic contexts that potentially shape and constrain farmer conceptualizations of sustainability, focusing on the contrast between the development and characteristics of the globalized system of industrial agriculture and more traditional systems-based methods considered to be alternative forms of agricultural production.
The study then uses this conceptual framework to integrate an historical account describing the development of agriculture in the Marys River region with contemporary ethnographic information collected through participant observation and semi-structured interviews with farmers to provide a more holistic understanding of contemporary definitions of agricultural sustainability.
This approach of integrating the qualitative information gathered from local farmers with historical and contemporary background information on land-use allowed for a better understanding of farmers' perspectives and definitions of sustainability. A principle finding from this research was that farmers throughout the Marys River region, regardless of farming styles and practices, consider sustainability primarily as the ability to continue farming into the extended future. Farmers' definitions of sustainability are inherently tied to the 'space' of the farm and these findings provide a common ground for dialogue among stakeholders with differing worldviews. This study helps to fill gaps in the existing literature on sustainability and agricultural land-use in the region; namely the perception and conceptualization of sustainability by its farmers. This more comprehensive understanding of how farmers relate to sustainability will help farmers, policymakers, and other institutions to better work together in making more informed decisions toward building stronger communities and developing a more sustainable bioregion within the global marketplace
Graduation date: 2013
2012-09-18T00:00:00ZApplication of biomarker compounds as tracers for sources and fates of natural and anthropogenic organic matter in the environmenthttp://hdl.handle.net/1957/32957
Application of biomarker compounds as tracers for sources and fates of natural and anthropogenic organic matter in the environment
Oros, Daniel R.
Determination of the source and fate of natural (higher plant lipids, marine
lipids, etc.) and anthropogenically (e.g., petroleum, coal emissions) derived
hydrocarbons and oxygenated compounds in the environment was accomplished
using gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS)
to characterize or identify molecular biomarkers to be utilized as tracers. The
distributions and abundances of biomarkers such as straight chain homologous series
(e.g., n-alkanes, n-alkanoic acids, n-alkan-2-ones, n-alkanols, etc.) and cyclic
terpenoid compounds (e.g., sesquiterpenoids, diterpenoids, steroids, triterpenoids)
were identified in epicuticular waxes from conifers of western North America
(natural emissions). These biomarkers and their thermal alteration derivatives were
also identified in smoke emissions from known vegetation sources (e.g., conifers,
deciduous trees and grasses) and were then applied as tracers in soils, soils that
contained wildfire residues and soil/river mud washout after wildfire burning. Where
possible, the reaction pathways of transformation from the parent precursor
compounds to intermediate and final alteration products were determined from GC-MS
data. In addition, molecular tracer analysis was applied to air, water and
sediment samples collected from a lacustrine setting (Crater Lake, OR) in order to
determine the identities, levels and fates of anthropogenic (i.e., petroleum
hydrocarbon contamination from boating and related activities) hydrocarbons in a
pristine organic matter sink. This work demonstrated that biomarker tracer analysis is
a useful tool for developing environmental management and pollution mitigation
strategies.
Graduation date: 2000
1999-09-24T00:00:00Z